1. Field of the Invention
The present invention relates to a refrigerator, and more particularly, to a method for controlling power saving operation of a refrigerator with two evaporators.
2. Background of the Related Art
Nowadays, with regard to the refrigerator for fresh conservation of food for a long time, there has been ceaseless development of the refrigerator for effective conservation of kimchi, a Korean specialty food. Though not shown, the refrigerator is provided with a body, a freezing chamber for frozen conservation of food, a refrigerating chamber for cold conservation of food, and a system of refrigerating cycle for cooling down the freezing chamber and the refrigerating chamber.
Referring to FIG. 1, the refrigerating cycle is provided with a compressor 1 for compressing refrigerant, a condenser 2 for isobaric condensing of the compressed refrigerant, a capillary tube 3 for adiabatic expansion of the condensed refrigerant, and a refrigerating chamber evaporator 4 and a freezing chamber evaporator 5 fitted to the refrigerating chamber and the freezing chamber respectively for isobaric evaporation of the expanded refrigerant.
Further to this, the refrigerating cycle has a three way valve 6 at a branch point for selective flow of the refrigerant condensed at the condenser 2 along branched flow passages to the refrigerating chamber evaporator 4 or the freezing chamber evaporator 5, a condenser fan 2a at the condenser 2 for cooling the condenser or the compressor 1, a refrigerating chamber evaporator fan 4a at the refrigerating chamber evaporator 4 for forced circulation of the air heat exchanged at the refrigerating chamber evaporator to accelerate heat exchange, and a freezing chamber evaporator fan 5a at the freezing chamber evaporator 5 for forced circulation of the air heat exchanged at the freezing chamber evaporator to accelerate heat exchange.
The operation of the foregoing refrigerating cycle will be explained.
First, in a RF cycle operation when both the refrigerating chamber evaporator 4 and the freezing chamber evaporator 5 are in operation, the three way valve 6 is opened to the refrigerating chamber evaporator for flow of the refrigerant, and the gaseous refrigerant compressed at the compressor us involved in a phase change into a liquid refrigerant as the compressed gaseous refrigerant passes through the condenser 2 where the compressed gaseous refrigerant heat exchanges with air outside of the refrigerator, the liquid refrigerant is involved in a pressure drop as the liquid refrigerant passes through the capillary tube 3, the liquid refrigerant is involved in a phase change into gaseous refrigerant as the liquid refrigerant passes through the refrigerating chamber evaporator 4 and the freezing chamber evaporator 5 in succession where the liquid refrigerant heat exchanges with the air in the refrigerating chamber/freezing chamber respectively, and the gaseous refrigerant returns to the compressor, again.
Second, in an ‘F’ cycle operation when only the freezing chamber evaporator 5 is in operation, the three way valve 6 is opened to the freezing chamber evaporator for flow of the refrigerant, and the gaseous refrigerant compressed at the compressor 1 is involved in a phase change into a liquid refrigerant as the compressed gaseous refrigerant passes through the condenser 2 where the compressed gaseous refrigerant heat exchanges with air outside of the refrigerator, the liquid refrigerant is involved in a pressure drop as the liquid refrigerant passes through the capillary tube 3, the liquid refrigerant is involved in a phase change into gaseous refrigerant as the liquid refrigerant passes through the freezing chamber evaporator 5 where the liquid refrigerant heat exchanges with the air in the freezing chamber, and the gaseous refrigerant returns to the compressor, again.
In the meantime, a related art method for controlling operation of the refrigerator will be explained with reference to FIG. 2.
When the refrigerator comes into operation after stop of the operation, a RF cycle operation is started as the compressor 1 is put into operation, when the freezing chamber evaporator fan 5a, the refrigerating chamber evaporator fan 4a, and the condenser fan 2a are put into operation on the same time.
During the RF cycle operation, if a temperature of the refrigerating chamber is below a set temperature, and a temperature of the freezing chamber is over a set temperature, the RF cycle operation is changed over to the F cycle operation, when the refrigerating chamber evaporator fan 4a is stopped, while the condenser fan 2a and the freezing chamber fan 5a continue the operation.
Thereafter, when the temperature of the freezing chamber is below the set temperature, the F cycle operation is finished, to stop the condenser fan 2a and the refrigerating chamber evaporator fan 5a. 
However, when the refrigerator comes into operation again to start the RF cycle, when the RF cycle operation is changed over to the F cycle operation, and when the operation of the refrigerator is finished to end the RF cycle, or the F cycle, the refrigerating chamber evaporator fan 4a, the freezing chamber evaporator fan 5a, and the condenser fan 2a are turned on/off on the same time, to cause the following problems.
First, when the operation of the refrigerator is stopped, as the refrigerant in the refrigerating cycle comes into a temperature equilibrium, the temperatures of the refrigerant in the refrigerating chamber evaporator 4 and the freezing chamber evaporator 5 rise.
Thereafter, when the refrigerator comes into operation again, to start the RF cycle operation, the high temperature refrigerant in the refrigerating chamber evaporator 4 flows to the freezing chamber evaporator 5, to elevate the temperature of the freezing chamber evaporator. In this instance, if the RF cycle operation and the freezing chamber evaporator fan 5a are put into operation on the same time, the air temperature in the freezing chamber is elevated substantially than the set temperature due to accelerated heat exchange, resulting in an increased power consumption.
Second, when operation of the refrigerator is stopped, as the operation of the compressor 1 and the freezing chamber evaporator fan 5a are stopped, and the refrigerant in the refrigerating cycle comes into the temperature equilibrium, the temperature of the refrigerant in the refrigerating chamber evaporator 4 or the refrigerant in the freezing chamber evaporator 5 rises, during which temperature rise, the refrigerant in the freezing chamber evaporator is in a liquid phase if the refrigerant in the freezing chamber evaporator has a temperature close to the freezing chamber set temperature. Consequently, when the refrigerator is put into operation again, the compressor 1 may be broken, or has a poor compression efficiency as the incompressive liquid refrigerant is introduced into the compressor 1.
When the refrigerator is stopped, refrigerant flow into the freezing chamber evaporator 5 is cut off, the operation of the freezing chamber evaporator fan 5a is stopped, and the temperature of the refrigerant remained in the freezing chamber evaporator 5 rises as the temperature equilibrium is established. However, the stop of the freezing chamber evaporator fan 5a results in abandonment of a refrigerating capability, a waste of energy, remained in the freezing chamber evaporator 5 as it is, because, though the refrigerant temperature starts to rise from a time operation of the refrigerator is stopped, the refrigerant temperature rises below a freezing chamber set temperature range up to a certain time period.
Third, when the RF cycle operation is discontinued as the RF cycle operation is changed over to the F cycle operation, or the operation of the refrigerator is stopped, the refrigerant flow into the refrigerating chamber evaporator 4 is cut off, and operation of the refrigerating evaporator fan 4a is stopped, to cause temperature rise of the refrigerant remained in the refrigerating chamber evaporator 4 as the temperature equilibrium is established. However, the stop of the refrigerating chamber evaporator fan 4a results in abandonment of a refrigerating capability, a waste of energy, remained in the evaporating chamber evaporator 4 as it is, because, though the refrigerant temperature starts to rise from a time operation of the refrigerator is stopped, the refrigerant temperature rises below a refrigerating chamber set temperature range up to a certain time period.
Fourth, right after operation of the condenser fan 2a is stopped on the same time with the stopping of the operation of the compressor 1, since pressures of a refrigerant outlet and inlet of the compressor are not balanced until a certain time period is passed when the pressures are balance at a pressure lower than a high pressure at the outlet and higher than a lower pressure at the inlet, the refrigerant flows from the outlet to the inlet of the compressor 1 for the certain time period, causing high pressure and high temperature refrigerant to flow into the low pressure and low temperature evaporators 4 and 5, that elevates temperatures of the evaporators 4 and 5.
That is, if the operation of the compressor 1 is stopped in the F cycle, high pressure and high temperature refrigerant flows into the low pressure and low temperature freezing chamber evaporator 5, to elevate the temperature of the freezing chamber evaporators, and, if the operation of the compressor 1 is stopped in the RF cycle, high pressure and high temperature refrigerant flows into the low pressure and low temperature refrigerating chamber evaporator 4 and the freezing chamber evaporator 5, to elevate the temperatures of the two evaporators. Consequently, the temperature in the freezing chamber or the refrigerating chamber exceeds the set temperature within a short time period, requiring an increase of a number of operation times of the compressor 1, with an increased power consumption.